Eighty-six years after its discovery, we finally get a close-up look at the dwarf planet at the edge of the Solar System. Not only is the surface a fascinating amalgam of mountains, craters, ice flows, and vast plains, but based on evidence from NASA’s New Horizons Spacecraft, Dr. Nimmo predicts a vast water ocean beneath the surface.

At the second Chesley Bonestell Memorial Lecture, the Friends of MIRA got a firsthand description by Clyde Tombaugh of how he discovered Pluto, a tiny dot in a sea of stars. Now, more than a quarter century later, the human desire to explore has revealed that dot as a complex planet with intriguing mysteries.

Dr. Nimmo is a professor of Planetary Sciences at the University of California at Santa Cruz.

His interests are in explaining the spectacular diversity of planets and moons in our solar system.